Definition
Chickenpox (varicella) is a highly infectious disease that usually occurs in childhood and is therefore a typical childhood disease. Chickenpox is caused by the chickenpox virus (varicella zoster virus). During the normal course of the disease, high fever and a characteristic itchy rash (exanthema) appear all over the body.
Whoever has had the disease once cannot fall ill a second time. A disease caused by the same virus, which remains in the body for life, is shingles. Chickenpox – as the first manifestation – can also appear only in adulthood, although under certain circumstances an altered and often severe course may occur.
Causes
The cause of chickenpox is identical in children and adults. Chickenpox infection (varicella) is caused by the varicella zoster virus. It belongs to the group of herpes viruses and is closely related to the herpes simplex virus (lip herpes, genital herpes) and the Epstein-Barr virus (Pfeiffer’s glandular fever).
Besides chickenpox, the chickenpox virus can also cause shingles. The virus enters the body through skin contact or by inhaling virus particles. From there it penetrates immune cells, the so-called mononuclear cells, which are found everywhere in the body.
Through these it is transported to nearby lymph nodes where it multiplies. Above a certain amount, the virus also reaches the spleen and the liver via the blood, where it can multiply to such an extent that it finally spreads via further mononuclear cells and via the blood into cells of the skin and mucous membrane. At the same time, the virus infects cells of the nervous system (nerve cell nodes in the area of the lumbar spine), where it survives for a lifetime and from where it can lead to shingles at an advanced age. In the skin and mucous membrane, the virus kills cells, causing the typical rash (cytopathogenic effect). A massive immune reaction when virus is in the blood or in many lymph nodes leads to fever.